The number of linkage group(s) present in Escherichia coli is

The correct option is A One
A linkage group is a linearly arranged group of linked genes which are normally inherited together except for crossing over. It corresponds to a chromosome which bears a linear sequence of genes linked and inherited together. Because the two homologous chromosomes possess either similar or allelic genes on the same loci, they constitute the same linkage group. Therefore, the number of linkage groups present in an individual corresponds to the number of chromosomes in his one genome (all the chromosomes if haploid or homologous pairs if diploid). It is known as the principle of limitation of linkage groups. E.coli contains a single chromosome. So, the number of linkage groups in E.coli is 1.